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Botany in the 17th and 18th Century or: the Basis of Systematics

Though many natural scientists in the 17th and 18th century were still very broadly educated, this was also the time of the beginning specialization. The first learned societies and academies were founded due to the need of mutual exchange. Decisive contributions on botany were made by the attempt to find a natural system for the great variety of plant species. Names to be mentioned in this context are JUNGIUS, RAY, and especially CARL v. LINNÉ. He established the binary nomenclature still used today and defined morphological terms. His name is also inevitably linked to the term species.

The relation between the great taxonomical groups of the plant kingdom had already been safely confirmed when DARWIN's theory of evolution was published.

Latin's significance declined. The times were a single man had to be able to represent all natural sciences alike came to an end. As time went by it became increasingly difficult to follow the progress of all science. Although at those times the specialisation took its beginning, a whole lot of outstanding natural scientists with a broad all-round education belong to this epoch: BACON (1561 - 1626), GALILEI (1564 - 1642), KEPLER (1571 - 1630), and DESCARTES (1596 - 1650). As the need for mutual exchange among Europe's scientists grew, academies and learned societies were founded. Among theme were:

Both academies perished soon due to the envy of the pontifical Curia. In Germany, J. JUNGIUS founded a scientific academy in 1622 at Rostock that, too, did not exist very long. The Thirty Years' War put an end to it. In 1663, an academy was founded at Oxford and was later on during the reign of Charles II, king of Great Britain and Ireland, changed into a Royal Society. It does, even today, belong to one of the most famous, internationally acknowledged societies of the world. In 1666, the Académie Française was founded in Paris.

The decisive contributions of this time to the progress of botany were the attempts to find a natural system for the great variety of plant species. CARL v. LINNÉ is thought to be the founder of modern plant systematics. His work is based on the results and recognitions of other researchers. In the following, some of the most famous will be introduced. Many of the questions left open by them became main subjects of research in the years to come especially in the late 18th century, in the 19th century, and in modern times.

One of the scientists upon whose work that of LINNÉ was founded, was J. JUNGIUS [1587 (Lübeck) - 1657 (Hamburg)]. JUNGIUS was no botanist, but, just like CESALPIN in Italy, the first German scientist to combine philosophically trained thinking with an exact observation of plants. He had the ability to define terms exactly and thus reduced the individual capriciousness of terminology in systematics. Although with him, too, scholastic body of thought can be found, he did trouble to detach himself from it. He was all the more influenced by mathmatical ways of thinking. To honor his work, some of his views are reviewed briefly in the following.

JUNGIUS found it to be logically correct that exactly defined terms, just like numbers, had to be reliable and unalterable values. He is thought to be the founder of a scientific artifical language that was later on developed further by RAY and perfected by LINNÉ.

JUNGIUS expected everything to be based on experiments and the conclusions drawn from them. Groundless authority was without value to him. Just as little he did allow the age or antiquity to be a cause of the validity of a rule.

He demanded that all parts of plants that were in their intrinsic nature the same though maybe different in shape or structure had to bear the same names. The whole terminology bases on this principle: leaves, leafstalk and their attachments, flowers, fruits and seeds were discussed by him.

He gave no introduction to his systematics, but critizised existing views and offered new suggestions:

"......if the plants are not classified as defined species and genera and have not been organized with a precise method - but with the capriciousness of some or other man - then the study of plants will become interminable. But an organisation into classes, species and genera puts up a border against infinity."

JUNGIUS doubted and discarded the grouping into trees, shrubs, half-shrubs and herbs and made it clear that half-shrubs and shrubs differ from herbs mainly in their "stamina" (perenniality).

He distinguished between important and unimportant features:

" The characteristics that are chosen to distinguish, like thorns, color, smell, taste, medicinal value, habitat, time of sprouting, as well as number of flowers and fruits are of no continuity and give no reasons for distinguishing between species."

He defined the plant as a living body that lacks the ability to feel. It is a body that is settled to a certain habitat or base from which it starts to feed, to grow and to reproduce. It feeds insofar as the taken food is converted into body material of the plant so that the material that is lost due to inner fire and warmth can be replaced. Owing to this process, the plant, too, gains heights and develops new body parts. The growth of plants differs from that of animals, since with plants not all parts of the body grow at the same time.

Reproduction is characterized as follows:

"A plant is said to reproduce, if it generates a new plant that is specifically similar to the old one."

As with CESALPIN, the term species is connected to reproduction.

The position of the first scientist to use flower properties as features of classification is due to the British researcher J. RAY (lat.: RAJUS, 1628 - 1705). He drew a clear line between mono- and dicotyledons after closely examining plant embryos. He did adopt the terminology from J. JUNGIUS and he additionally did influence C. V. LINNÉ. RAY established six rules (1703) which belong to the fundamental principels of plant systematics till today:

  1. Names have not to be changed to avoid confusion and errors.
  2. Characteristics have to be exactly and distinctively defined which means that those basing on relative relations like heights are not to be used.
  3. Characteristics have to be easily detected by everybody.
  4. Groups that are accepted by almost all botanists have to be kept.
  5. It has to be taken care that related plants will not be seperated, unnatural ones and those that are different are not to be united.
  6. Characteristics shall not without necessity be increased in number, but only as many shall be used as are necessary to make a reliable classification.

Based on these rules, he did try to deduce wider relationships (families, genera), introduced definitions for several genera and developed a key for the determination of plants that was founded on the principles mentioned above. Despite many positive ideas, he did, too, still adhere to the separation of wooden plants and herbs.

The problem of relation, the definitions of genera and families was also approached by a number of other botanists. The physician and philosopher A. BACHMANN from Leipzig (lat. RIVINUS, 1652 - 1725) proposed a binary nomenclature without sticking to it himself. He postulated that the name of the genus had to be given to every species, followed by the specifical name of the species itself as an adjective.

Still to be mentioned is the Frenchman J. P. TOURNEFORT (1656 - 1708). By means of traveling (France, Spain, Portugal, The Netherlands, Britain, Greece, Asia Minor, Africa) he gained a broad knowledge of plant species. From his journey to Greece/Asia Minor alone he returned with more than 1300 new species. He, too, was trying to organize the great variety of plants in a natural system. He noticed, just as RAY had done, the importance of the flower's structure for his intention. Especially the fused petals and the differences in the seat of the ovule were of closer interest to him. Genera were defined exactly and the diagnosis was illustrated by detailed drawings of the ovule. Nonetheless he did not pay much attention to the single species: he just named them as belonging to a certain genus.

Although the drawing up of botanical systematics was one of the main aims of botanical research of this time, all attempts to deduce natural relations failed due to the premises which were still partly wrong. It was believed that natural relations could be come to by a number of easily perceived features whose value for systematics was still a priori set in a subjective choice. The change came with CARL v. LINNÉ.

CARL v. LINNÉ [1707 (Rashuld, South Sweden) - 1778 (Uppsala)] was professor of anatomy and medicine and later became professor of botany at the University of Uppsala. He is regarded as the founder of systematics, both for animals and plants. His biographer K. HAGBERG wrote in 1946:

"Whoever wants to write an exhaustive book about CARL LINNAEUS that would meet all necessary requirements would have to have at his disposal a profound knowledge of all humanistic disciplines. He would have to be a physician and, moreover, he would have to master the history of medicine right from its beginning, he would have to be able to talk Latin, would have to be on familiar terms with all the scientific qualifications necessary to gain a comprehensive understanding of zoology, botany, and geology and, what is more, would additionally have to do ethnological research. In-depth and lengthy philosophical and theological studies would be among those essential, too. Finally, the person should have a thorough knowledge of literature and man, should be nature-loving, should like to wander and, if possible, have something of a poet."

CARL v. LINNÉ's main work was published in 1735. It is called Systema naturae. In 1759, it was already in its 10th edition. Among his other important works are: Fundamenta botanica (1737), Bibliotheca botanica (1736), Flora lapponica (1737), Hortus Cliffortianus (1737), Critica botanica (1737), Flora svesica (1745), Philosophica botanica (1751) and Species plantarum (1753).

Under his leadership, Uppsala developed into a centre of international botanical research. His pupils enriched the system of LINNÉ by introducing foreign plants. LINNÉ himself made many contributions to the systematics both of plants and animals, the consequences of which were far-reaching. Among his merits is a compilation of all his work. The following innovations are attributed to him.

  1. Stringent carrying out of the binary nomenclature of the species in connection with the careful methological characterisation of the genera and the species which he tried to extend to all plant kingdom known at his time.

  2. Terminology. Based on works of JUNGIUS, he defined morphological terms. With the description of the organs of fructification (flowers) he goes far beyond the work of his predecessors. The frutification of the plants, he writes, is a temporary part that ends the old and lets the new begin. Some details:

    • Calyx: forms the boundary of the bark during frutification
    • Sepals and petals
    • Stamen: produces pollen
    • Pistil: is attached to the fruit and receives the pollen. For the first time ovary, style and stigma are clearly seen as different

    • Pericarp: the ovule that containes the seeds. The fruit is described as an organ of its own

    • Seed: part of the plant that falls off
    • Receptacle: all parts that combine the organs of frutification
    • His definitions became the standard. Without them, it would, even today, be impossible to describe any plant.

  3. The name of LINNÉ is in addition inextricably linked to the term "species" and to the idea of a constancy of species. He postulated that as many species existed as had been created during genesis. But in the last edition of "Systema naturae" he dissociates himself a little from this view. He defines features that have been changed due to the influence of climate, sun, wind, warmth and humidity as varieties. They can differ from the average type by heights, filled or frizzy flowers, colors, taste or smell.

  4. He thought the main aim of botany to be the establishing of a natural system. In one of his attempts, he does try to put up a system founded on the distribution, number and growing together of petals and stamen (sexual system). He noticed the weakness of the system and searched in vain for alternatives. His definition of the constancy of a species was an obvious obstacle, since it denied natural relations, which are essential for the developement of a natural system. This contradiction remained for a long time and was not resolved until 1859, when C. DARWIN came along.

After the guidelines for systematics had been developed, the classification of plants made speedily headway. A. L. DE JUSSIEU (1748 - 1836) designed familiy diagnoses, in which the features of the flower, the fruit and the vegetative organs were all taken into account. Instead of merely enumerating small groups and place them next to each other, he did introduce a conception of the plant kingdom as devided into bigger and gradually subordinated groups. LINNÉ had explicitly found this to be beyond his limits.

© Peter v. Sengbusch - Impressum